Why does chmod require disk space? Not-in-place algorithm

chmodnfsquota

I try to chmod some files and I get the error "disk quota exceeded":

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It's true that I don't have that much space remaining in the filesystem where I use chmod, namelynfs.mit.edu:/export/evodesign/beatdb (which is an NFS), either in terms of bytes or in terms of inodes:

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But why does chmod need more space?

I use Ubuntu 12.04.

Edit: Some more info following the comments:

1) I don't know the OS of the NFS server (nmap -O nfs-server-ip didn't return anything)

2) The NFS protocol in use by a mounted NFS filesystem is NFSv3:

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3) quota -v:

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4) I don't have any /var/log/messages logs, I do have some /var/log/syslog logs but nothing looks weird there.

Best Answer

As noted in the comments: it seems likely that you're over quota, and the filesystem is rejecting your write for this reason.

There are many filesystems where all writes are journaled, with the old version kept. One such filesystem is ZFS - read about the interaction between ZFS snapshots and quotas.

(However, the problem may just be that the NFS server rejects all writes when you're over quota).

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